A year ago, some of the world's largest email services began ordering the quarantine or deletion of messages sent in their names. The result of this mass execution is being hailed as a resounding success.

On Wednesday, DMARC, an industry group founded by leading technology, financial service, social and media companies in early 2012 to fight email fraud, announced that its message authentication technology now protects almost 2 billion of the world's 3.3 billion consumer inboxes and 80% of the consumer inboxes in the United States.

DMARC stands for domain-based message authentication, reporting and conformance. Supported by email security providers Agari, Cloudmark, Return Path and Trusted Domain Project, it is a framework by which email senders can authenticate legitimate messages and can exchange information with receiving entities about how to handle unauthenticated messages -- monitor them, quarantine them or delete them.

In just the last two months of 2012, 325 million messages were rejected by mailbox providers for being unauthenticated. Such messages are often spam, phishing attacks or other forms of brand or domain spoofing -- in this case, 49 million of the rejected messages were from highly phished domains. Some of these messages may come from within an organization, via unsecured mail servers, while others may carry forged header information or come from confusingly similar domains.

"What brands are doing is shutting down these avenues of large-scale, orchestrated attacks," said Trent Adams, chair of DMARC.org and senior policy advisor at PayPal, in a phone interview. "The mailbox providers finally have a way to take definitive action on fraudulent mail."

Though based on authentication technologies, like SPF and DKIM, DMARC's value comes from combining message security with collaboration and business intelligence. Email senders that publish DMARC policies receive feedback reports from DMARC-compliant message recipients about unauthenticated messages purporting to come from any of the sending organization's domains.

These reports provide visibility into an organization's email stream and allow the organization to take enforcement action if necessary, explained Adams.

Such data matters to businesses because it's often a surprise. Reviewing a case study provided by Message Bus, Adams described how an unnamed, large, international conglomerate decided to test whether its domains were being spoofed. The company deployed a DMARC monitor record to gather information about unauthenticated email messages that people were receiving from its domains. It found that only 36% of messages that purported to come from the company actually originated from company servers. About 61% of the messages were from unknown and possibly malicious senders, while 3% was forwarded, through discussion lists or other mechanisms.

"That kind of business intelligence is a wakeup call to any organization," said Adams. "This is not an edge case. We hear this time and time again. Companies put out a monitor policy to see what the waters look like and they find they have a much larger problem."

Adams also cited the example of an unnamed, large, online auction company that saw a 32% decrease in phishing attempts and 62% less unauthorized account access following DMARC deployment. Coincidentally, eBay was an early DMARC adopter.

Krish Vitaldevara, principal group program manager for Microsoft's Outlook.com, said that the need for the security DMARC provides is reflected in how rapidly email senders and receivers are adopting the framework.

While 100% adoption and an end to domain spoofing may be too much to hope for, Adams likens DMARC to an inoculation campaign. If you can get a large enough percentage of the population inoculated, then everyone will be protected, he said.